Plastic or vinyl rail assemblies, for example for use in fencing and decking, are gaining popularity due to their durability and pleasant appearance. Unlike wood used in conventional fencing or decking rail assemblies, the plastic or vinyl components do not require post-sale painting and weatherproofing and will not rot over time. Rail assemblies feature horizontal rails supported on and extending between vertical posts spaced apart along a straight line. Plastic or vinyl posts are usually manufactured to be hollow, and as such are usually fitted over and supported about rigid pipes that provide the necessary strength to support the final structure. The rigid pipe may be supported by driving a lower end thereof a distance into the ground or by anchoring it to some kind of foundation or support surface that must be provided on/in/above the ground. Different devices have been developed for positioning the hollow post about the pipe for each of these situations.
U.S. Pat. No. 6,213,452 discloses a base plate adapted to engage both the hollow vinyl post and the interior support pipe to support them to extend upward from a horizontal support surface. Installation of a series of posts to create a substantially horizontal rail assembly may prove difficult in situations where the ground surface features irregularities that deviate from the horizontal, as the support surfaces for some base plates may have to be built up from or recessed into the ground to support neighbouring posts at a common elevation. Building up of a base plate may require additional materials to do so and recessing a base plate may require accurate earth removal to form a horizontal surface at a specific depth. Adjustment of relative tilt between longitudinal axes of the post and pipe is achieved through adjustment of screws extending radially outward from the pipe near an upper end thereof, such that each screw engages an inner surface of the hollow post at a desired distance from the pipe. Allowing misalignment of the axes of the post and pipe allows the post to extend vertically about the pipe even if the pipe is not perfectly vertical. Access to the screws likely requires either removal of the hollow post from about the pipe or formation of openings in the hollow post through which they can be accessed.
U.S. Pat. No. 6,523,808 discloses a fixture for positioning the hollow post concentrically about the pipe regardless of how the pipe is anchored at its lower end. The fixture features a round inner cylinder which is slid over the pipe and fastened thereto and a larger round outer cylinder that engages inner surfaces of the hollow post to retain it at a fixed distance from the pipe in all directions. Two fixtures are used to position the post near the top and bottom ends thereof. The post is lowered over the fixtures until a bottom end thereof engages a base surface for support thereon. For the reasons provided in the preceding paragraph, providing a series of equally elevated horizontal support surfaces over a distance may require substantial effort, materials and/or time.
Mounting devices similar to the fixture described above have been developed in which the round inner cylinder is replaced with an oblong collar having an inner width substantially equal to an outer diameter of the pipe so that the axes of the pipe and mounting device can be misaligned by movement of the pipe within the collar before fastening of the two. This allows relative positioning of the hollow post and pipe such that the post can be disposed in a vertical orientation even if the pipe about which it is disposed is not perfectly vertical. It should be appreciated that after fastening, further adjustment of the mounting device requires unfastening it from the pipe and moving it relative thereto for refastening. Such further adjustment therefore would require access to the mounting device, for example by either at least partial removal of the post from about the pipe or the formation of openings in the post to access the mounting device fastener therein.